1. Field of the Invention
The present invention relates to manufacturing backplanes for large-scale flat panel displays and, more particularly, to a system and method of forming a large-area backplane by use of one or more small-area shadow masks.
2. Description of Related Art
Active matrix backplanes are widely used in flat panel displays for routing signals to pixels of the display in order to produce viewable pictures. Presently, such active matrix backplanes are formed via a photolithographic manufacturing process, which has been driven in the market by the demand for higher and higher resolution displays which are not otherwise possible with other manufacturing processes. Photolithography is a pattern definition technique which uses radiation, such as ultraviolet (UV) radiation, to expose a layer of resist that is deposited on the surface of a substrate. Exemplary photolithography processing steps to produce an active matrix backplane include coat photoresist, pre-bake, soak, bake, align/expose, develop, rinse, bake, deposit layer, lift off photoresist, scrub/rinse and dry. As can be seen, the photolithographic manufacturing process for producing an active matrix backplane includes numerous deposition and etching steps in order to define appropriate patterns of the backplane.
Because of the number of steps required to form an active matrix backplane with the photolithographic manufacturing process, foundries of adequate capacity for volume production of backplanes are very expensive. An exemplary partial list of equipment needed for manufacturing active matrix backplanes utilizing the photolithographic manufacturing process includes glass-handling equipment, wet/dry strip equipment, glass cleaning equipment, wet clean equipment, plasma chemical vapor deposition (CVD) equipment, laser equipment, crystallization equipment, sputtering equipment, ion implant equipment, resist coater equipment, resist stripping equipment, developer equipment, particle inspection equipment, exposure systems, array filet/repair equipment, dry etch systems, anti-electrostatic discharge equipment, wet etch systems and a clean oven. Furthermore, because of the nature of the photolithographic manufacturing process, the foregoing equipment must be utilized in a class one or class ten clean room. In addition, because of the amount of equipment needed and the size of each piece of equipment, the clean room must have a relatively large area, which can be relatively expensive.
A vapor deposition shadow mask process has been used for years in microelectronics manufacturing. The vapor deposition shadow mask process is significantly less costly and less complex than the photolithography process. However, heretofore, the vapor deposition shadow mask process has not been favored by those of ordinary skill in the art for fabricating large-area backplanes. Publications disclosing vapor deposition shadow mask processes as well as related processes are disclosed in U.S. Patent Application Publication No. 2003/0193285; U.S. Patent Application Publication No. 2002/0011785; U.S. Pat. Ser. No. 6,592,933; U.S. Pat. No. 6,384,529 and U.S. Pat. No. 4,919,749.
What is, therefore, needed, and not disclosed in the prior art, is a method and apparatus for fabricating large-area backplanes via the vapor deposition shadow mask process, rather than utilizing the more costly photolithographic process. Other needs that the present invention fulfills will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.